1981 Rochester Qjet vs 1980 or 1979 Rochester Qjet

[criegs]

Here's a question...... I have a 1981 Rochester Qjet controlled by the computer, could you discconnect the computer from the carb and run a 1980 or 1979 or earlier Rochester Carb? I have a mixture control value on the 81 carb that may need to be replaced. It's disconnected now in order to let it run, but I think it's running rich without it connected, and the gas milage isn't the greatest. The cost of the mixture control valve part alone is about half the cost of a built Rochester. Any input would be great. Thank you in advance.

 

[Peer81]

Yes, you could change the 81 E4ME carb with a 80 or 79 normal Q-jet, you will also need to replace the HEI ignition to one that isn't controlled by the ECM.
I had the same problem, running very rich, tuning the carb wasn't possible and the A/F solenoid was broken.
I bought another E4ME for about $20 and that solenoid was working fine. I would say, look at junkyards to find them. A E4ME carb is a good carb!

Groeten Peter

 

[Hib Halverson]

I agree with "Peer81".

Your car will run nicer at part throttle and get better gas mileage if you run the E4ME.

The computer only controls the primaries. You can "tune" the secondaries as you can with other Quadrajets.

 

[criegs]

Yes, you could change the 81 E4ME carb with a 80 or 79 normal Q-jet, you will also need to replace the HEI ignition to one that isn't controlled by the ECM.
I had the same problem, running very rich, tuning the carb wasn't possible and the A/F solenoid was broken.
I bought another E4ME for about $20 and that solenoid was working fine. I would say, look at junkyards to find them. A E4ME carb is a good carb!

Groeten Peter

Thank you for the information and your insight. The owner before me had changed the dizzy to HEI and has disconnected it from the computer. Either why I think I'll take your advise and hit the salvage yard there is a feww around here or maybe even purchase the part for my local parts store. Thanks again

 

[criegs]

I agree with "Peer81".

Your car will run nicer at part throttle and get better gas mileage if you run the E4ME.

The computer only controls the primaries. You can "tune" the secondaries as you can with other Quadrajets.

Thank you for your advice. I'll plan to keep the E4ME. I'll pick up a rochester carb book for tuning in the carb for best results.

Thanks again

 

[Yoda]

Good Morning,

This may be insignificant or not. You say the prior owner "disconnected the computer from the carb" does this mean that you are looking at putting a 1981 E4MEcarb on a 1980 CA car (305 LG4)?

I have no idea if this needs to be a consideration or not, someone with more experience and knowledge would need to answer that question. I just raise this issue, because the LG4 1980 Corvette has the computer, and as I recall these cars had a different carb, because they were all automatics and carbs for the 1981 4 Speed (E4ME) were just a bit different because of the Automatic Transmission verse's the 4-Speed.

Bud

 

[criegs]

Good Morning,

This may be insignificant or not. You say the prior owner "disconnected the computer from the carb" does this mean that you are looking at putting a 1981 E4MEcarb on a 1980 CA car (305 LG4)?

I have no idea if this needs to be a consideration or not, someone with more experience and knowledge would need to answer that question. I just raise this issue, because the LG4 1980 Corvette has the computer, and as I recall these cars had a different carb, because they were all automatics and carbs for the 1981 4 Speed (E4ME) were just a bit different because of the Automatic Transmission verse's the 4-Speed.

Bud

No the prior owner disconnected the distrubutor form the computer. The carb is an 1981 E4ME that was hooked to the computer until what I believe the mixture control solenoid failed. The reason this is thought is because of it not running well. I disconnected it and runs out great.

I have an automatic transmission so I also need to consider torque convertor lockup also.

Thank for your consideration

 

[Peer81]

Mixture Control Solenoid Kit - Rochester Quadrajet and DualJet



Groeten Peter

 

[TimAT]

Even as those early computers were way behind the curve, things did all work together- the computer still controlled mixture and ignition timing, sensed throttle position and controlled the trans lockup. Everything still worked together. Not having any one of the needed sensors (TPS,Temp,VSS, just off the top) would cause a host of driveability problems.

 

[HammerDown]

Even as those early computers were way behind the curve, things did all work together- the computer still controlled mixture and ignition timing, sensed throttle position and controlled the trans lockup. Everything still worked together. Not having any one of the needed sensors (TPS,Temp,VSS, just off the top) would cause a host of driveability problems.

Darn...so are you saying for my 81 (auto) I wouldn't be able to remove the computer controlled Guadrajet and dizzy for a earlier non-computer controlled Quad and Dizzy and have a functional trany?